#pragma once
#include<iostream>
#include<vector>
using namespace std;
namespace Hash_Bucket
{
	template<class K>
	struct HashFunc
	{
		size_t operator()(const K& key)
		{
			return (size_t)key;
		}
	};
	template<>
	struct HashFunc<string>
	{
		size_t operator()(const string& key)
		{
			size_t hash = 0;
			for (auto& e : key)
			{
				hash *= 131;
				hash += e;
			}
			return hash;
		}
	};
	template<class K,class V>
	struct HashNode
	{
		pair<K, V> _kv;
		HashNode<K, V>* _next;
		HashNode(const pair<K,V>& kv)
			:_kv(kv),
			_next(nullptr)
		{}
	};
	template<class K,class V,class Hash = HashFunc<K>>
	class HashTable
	{
	public:
		typedef HashNode<K, V> Node;
		inline unsigned long __stl_next_prime(unsigned long n)
		{
			// Note: assumes long is at least 32 bits.
			static const int __stl_num_primes = 28;
			static const unsigned long __stl_prime_list[__stl_num_primes] =
			{
				53, 97, 193, 389, 769,
				1543, 3079, 6151, 12289, 24593,
				49157, 98317, 196613, 393241, 786433,
				1572869, 3145739, 6291469, 12582917, 25165843,
				50331653, 100663319, 201326611, 402653189, 805306457,
				1610612741, 3221225473, 4294967291
			};
			const unsigned long* first = __stl_prime_list;
			const unsigned long* last = __stl_prime_list +
				__stl_num_primes;
			const unsigned long* pos = lower_bound(first, last, n);
			return pos == last ? *(last - 1) : *pos;
		}
		HashTable()
		{
			_tables.resize(__stl_next_prime(0));
		}
		~HashTable()
		{
			for (size_t i = 0; i < _tables.size(); i++)
			{
				Node* cur = _tables[i];
				while (cur)
				{
					Node* next = cur->_next;
					delete cur;
					cur = next;
				}
				_tables[i] = nullptr;
			}
		}
		bool Insert(const pair<K, V>& kv)
		{
			if (Find(kv.first))
				return false;

			Hash hs;
			if (_n == _tables.size())
			{
				//扩容
				size_t newsize = __stl_next_prime(_tables.size() + 1);
				vector<Node*> newtables(newsize, nullptr);
				// 将旧表的数据移动到新表
				for (size_t i = 0; i < _tables.size(); i++)
				{
					Node* cur = _tables[i];
					while (cur)
					{
						Node* next = cur->_next;
						size_t hashi = hs(cur->_kv.first) % newtables.size();
						cur->_next = newtables[hashi];
						newtables[hashi] = cur;
						cur = next;
					}
					_tables[i] = nullptr;
				}
				_tables.swap(newtables);
			}

			size_t hashi = hs(kv.first) % _tables.size();
			Node* newnode = new Node(kv);
			newnode->_next = _tables[hashi];
			_tables[hashi] = newnode;
			++_n;
			return true;
		}
		Node* Find(const K& key)
		{
			Hash hs;
			size_t hashi = hs(key) % _tables.size();
			Node* cur = _tables[hashi];
			while (cur)
			{
				if (cur->_kv.first == key)
				{
					return cur;
				}
				else
				{
					cur = cur->_next;
				}
			}
			return nullptr;
		}
		bool Erase(const K& key)
		{
			Hash hs;
			size_t hashi = hs(key) % _tables.size();
			Node* cur = _tables[hashi];
			Node* prev = nullptr;
			while (cur)
			{
				Node* next = cur->_next;
				if (cur->_kv.first == key)
				{
					if (prev == nullptr)
					{
						_tables[hashi] = next;
					}
					else
					{
						prev->_next = next;
					}
					delete cur;
					--_n;
					return true;
				}
				prev = cur;
				cur = next;
			}
			return false;
		}
	private:
		vector<Node*> _tables;
		size_t _n = 0;
	};
}